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Pak. J. Bot., 42(6): 4071-4078, 2010.

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ENHANCEMENT IN SEED GERMINABILITY OF RICE (ORYZA SATIVA L.) BY PRE-SOWING SEED TREATMENT WITH NITRIC OXIDE (NO) UNDER SALT STRESS

NOMAN HABIB¹, MUHAMMAD ASHRAF^1,2,* AND MUHAMMAD SAJID AQEEL AHMAD¹

Abstract: The seeds of two fine-rice (Shaheen and PB-95) and two coarse rice (IRRI-6 and KS-282) cultivars were soaked in varying levels of nitric oxide (NO) (0, 0.05, 0.1, 0.2, 0.3, 0.4 and 0.5 mM) and then exposed to 80 mM NaCl in sand culture. Application of salt stress significantly reduced seed germinability parameters of all four rice cultivars in terms of percent seed germinated, germination index and seedling fresh and dry weights. The toxic effects of salt stress in reducing seed germinability were greater in fine rice cultivars (Shaheen and PB-95) as compared to those in coarse ones (IRRI-6 and KS-282). Although, the application of lower levels of nitric oxide (0.05, 0.1 and 0.2 mM) as pre-sowing seed treatment showed a significant improvement,  0.1 and 0.2 mM NO were found to be the most effective in improving seed germinability under salt stress. With a further increase in NO concentration (0.3 mM) as pre-sowing seed treatment, the seed germinability parameters differed non-significantly from those of control plants, while the highest levels (0.4 and 0.5 mM) showed significant inhibitory effects on seed germination and early seedling growth. It was concluded that lower levels of NO (0.1 and 0.2 mM) could be used to effectively enhance seed germination of rice plants under salt stress.

¹Department of Botany, University of Agriculture, Faisalabad

¹Second affiliation: Department of Botany and Microbiology, King-Saud University, Riaydh, Saudi Arabia

*Corresponding author’s e-mail: ashrafbot@yahoo.com